Centrifugal cutting pump



2 SheetsSheet l A. CJ'IDURDIN, JR

GENIRIFUGAL CUTTING PUMP Filed Jan'. 18, 1943 Man-ch20, 1945.

Patented Mar. 20, 1945.

CENTRIFUGAL CUTTING PUMP Augustus C. Durdin, Jr., Lincolnwood lll.Application January 18, 1943, Serial No. 472,690

Claims. (01. 103-111) This invention relates to centrifugal cuttingpumps. Pumps of this character are usually used for pumping liquidscontaining solid and semi,

solids, such as sludge, and one object of this invention is to increasethe eiliciency of such pumps and to more efiectively reduce the solidsinto small pieces so that they may readily pass with the flow of liquidthrough the pump and be pumped to some other station for furthertreatment. Another object is to prevent clogging and to prevent windingof stringy material around a rotating elements of the pump.

Other objects and advantages will appear in the course of thisspecification and with said objects and advantages in view thisinvention con sists in the several novel features hereinafter fully setforth and claimed.

One embodiment of the invention is clearly illustrated in theaccompanying drawings, in which:

Fig. 1 is a view, partly inside elevation and partly in central,vertical, longitudinal section of acentrifugal cutting pump embodyingthe invention.

Fig. 2 is a vertical cross section thereof taken on the line 2-2 of Fig.1.

Fig. 3 is a vertical longitudinal section taken on the line 3--3 of Fig.2..-

Fig. 4 is a detail cross section of a certain cutting blade taken on theline 4-4 of Fig. 1.

Referring to said drawings. which are merely illustrative of theinvention, the reference'character 5 designates the main member of thepump casing, usually cast with a base 6, a suction inlet 1, whichterminates in an inlet chamber 8 that leads to the eye 9 of the pumpimpeller H), which is contained in a volute chamber II. the wals of whch may be cast integral with the other walls of the pump casing. Oneside of the volute chamber is closed by a head I! bolted to the wall ofthe volute chamber. The latter terminates in a discharged outlet l3.

The outer side wall of the inlet chamber 8 has an opening which isclosed by a head l4, bolted to said wall of the inlet chamber. The headsl2, M are cast with stufiing boxes l5 for the pump shaft 16, and withbearing brackets ii that include bearing boxes iii in which the pumpshaft is journalled. The pump shaft extends through the inlet chamberand the volute chamber, and keyed or otherwise secured upon the shaft inthe inlet chamber is a rotating cutting member i9 which extends from theouter side wall of the inlet chamber, through a cutting ring 20, to theeye of the impeller. The latter is keyed upon the shaft and is held incontact with the cutting member l9 by a nut 2| threaded upon the shaft.The cutting member bears against the flange 2la on the shaft.

The body 22 of the cutt ng element is tapered and tapers toward theimpeller. It is cast or otherwise provided with cutting blades 23disposed helically about the tapered body.- The cutting blades 23co-operate with a stationary cutting bar 24 which extends parallel withthe 'axis of the rotating cutting member and is seated in a re- .ces 25formed on the inner face'of the part 26a of the wall 26 of the inletchamber. The

- cutting bar is. rigidly secured in place by bolts 21 that extendthrough said part 26a of the wall of the inlet chamber. The-cutting faceof the cutting bar is disposed in close proximity to the cutting facesof the cutting blades, to provide a shearing action on material caughtbetween the blades of the rotat ng cutting member and the cutting bar.One side of the cutting bar is shown as sloping toward the rotativecutting element with the part 28 of the suction inlet wall 29 slopingalong the same plane and disposed flush with said sloping face of thecutting bar. The rotating cutting member directs liqu ds along saidsloping faces and sets up turbulence whereby material caught on thecutting bar' is washed therefrom, enabling it to pass with the flowingstream to the eye of the impeller.

The cutting ring 20 is notched to provide a multiplicity of cuttingteeth 30 on its internal side which teeth co-operate with the blades ofthe rotating cutting memberto comminute or reduce any material that mayproject beyond the cutting faces of the blades. The cutting ring isshown as flanged and is rigidly seated in a bored part 3| of the wall ofthe inlet chamber.

To prevent pieces of material from lod n between the end of the rotatingcuttin member and adjacent side wall of the inlet chamber, a cuttingblade 32 is provided. which is seated in a recess formed in the sidewall of the inlet chamber, and secured therein by a screw or otherwise.The cutting blade 22 co-operates with the rotating cuttng member toshear oii any material that might enter between the side wall androtating cutting member.

The impeller may be provided with any desirable number of impellerblades 33 but the rotating cutting member is formed with a greaternumber of cuttingblades than the number of impeller blades, certain ofthe cutting blades joining or abutting against the impeller blade andthe blades, the solids are other cutting blades terminating at thespaces between the impeller blades.

By having a relatively large number of cutting reduced mor thoroughlyand the cut up mas is distributed in the channels between the impellerblades, thereby preventin g clogging of the impeller.

The bottoms of the notchesbetween therteeth 30 of the cutting ring slopeaway from the edge of the cutting ring toward the inner face thereof. toenable material which is cut off by the teeth to freely pass into thechannels between the cutting blades of the rotating cutting member.

Power from any suitable source may be applied to the pump shaft. Inoperation liquids containing solids and semi-solids flow in through thesuction inlet and enter the inlet chamber, passing through the channelsbetween the blades of the rotating cutting member to the eye of theimpeller, from which they are discharged by the impeller into the volutechamber and thence discharged through the discharge outlet.

Solid and semi-solid materials carried around by the rotating cuttingmember and caught be-' tween the blades thereof and the stationarycutting bar are sheared off, and the pieces which lodge on the slopingface of the stationary cutting bar are washed from the same and passwith the liquids'to the eye of the impeller and are distributed betweenthe impeller blades. Pieces caught betweenthe cutting blades and'theteeth of the cutting ring are further reduced and pass with the flowingstream to the eye of the impeller.

I claim as Patent: g

1. In a centrifugal cutting pump the combination with a pump casinghaving a suction inlet, an inlet chamber formed with a top wall whichinclines upwardly from the suction inlet and terminates in a downwardlyinclined wall at the inlet chamber, a volute chamber and a discharge newand desire to secure by Letters outlet, of a shaft mounted to rotate insaid casing, a rotating cutting member mountedon said shaft in saidinlet chamber, said rotating cutting-member having a plurality ofcutting blades disposed helically about the body thereof, a stationarycutting bar having one face flush with the inclined terminal end of saidtop wall and mounted in the inlet chamber and co-operating with saidrotating cutting member to'reduce solids, and a separately formedimpeller mounted on said shaft in the volute chamber with its eyecommunicating with the channels between the blades of the rotary cuttingmem-' ber, said impeller having impeller blades, the

inner ends of which join with adjacent ends of V some of the cuttingblades, other cutting blades terminating at the spaces between theimpeller blades. g

2. In a centrifugal cutting pump the combination with a pump casinghaving a suctioninlet, an inlet chamber formed with a top wall whichinclines upwardly from the suction inlet and terminates in a downwardlyinclined wall at the inlet chamber, a volute chamber and a dischargeoutlet, of a shaft mounted to rotate in said casing, a rotating cuttingmember mounted on said shaft in said inlet chamber, said rotatingcutting member having a plurality of cutting blades disposed helicallyabout the body thereof, a stationary cutting bar having one face flushwith the inclined terminal end of said top wall and mounted in the inletchamber and co-operating with said rotating cutting member to reducesolids, and a separately formed impeller mounted I on said shaft in thevolute chamber with its eye terminates in a downwardly inclined wall atthe inlet chamber, a volute chamber and a discharge outlet, of a shaftmounted to rotate in said casing, a rotating cutting member mounted onsaid shaft in the inlet chamber, said rotating cutting member havingcutting blades disposed helically about the body of the rotating cuttingmember, with channels between the blades, a stationary cutting bardisposed above the rotating cutting member and paralleling the axis ofthe same and secured to the top wall of the inlet chamber in shearingrelation with respect to the cutting blades, one face of said top wallof the inlet chamber being flush-with an inclined side face of thecutting bar and inclining upwardly toward the suction inlet, and animpeller mounted on said shaft with its eye opening to said channels.

4. In a centrifugal cutting pump the combination with a pump casinghaving a suction inlet, an inlet chamber formed with a top wall whichinclines upwardly from the suction inlet and terminates in a downwardlyinclined wall at the inlet chamber, a volute chamber and a dischargeopening, of a shaft mounted to rotate in said casing. a rotating cuttingmember mounted on said shaft in said inlet chamber, said rotatingcutting member having cutting blades disposed helically about the bodyof the rotating cutting member with channels between the blades, astationary cutting bar disposed above the rotary cutting member andparalleling the axis of the same and secured to a wall of the inletchamber in shearing relation with respect to said cutting blades, oneside face of said cutting bar sloping toward the rotating cutting memberand ting member.

5. In a centrifugal cutting pump the combination with a pump casinghaving an inlet chamber, of a shaft mounted to rotate in said casing, arotating cutting member mounted on said shaft in said inlet chamber,said cutting member having cutting blades disposed helically about thebody thereof, a cutting ring mounted in said casing at one side of theinlet chamber and being formed with cutting teeth on its internal faceco-operating with the cutting blades to reduce solids, and an impellermounted on said shaft. in the casing, with its eye in communication withthe space between the internal face of the cutting ring and the body ofthe rotating cutting member.

AUGUSTUS C. DURDIN, JR.

